To better serve Dual Language Learners (DLLs), research needs to focus on how having access to two languages uniquely affects their learning and development. The overarching purpose of this project is to increase the understanding of classroom factors and processes that can support the language and socio-emotional development of DLLs. Toward this end, this project will examine teacher-child interactions occurring with Spanish- English DLLs and their relations to children's school readiness. The proposed project will be guided by the following objectives: 1) To employ a mixed-methods approach using both primary data and a secondary dataset, the Head Start Family and Child Survey (FACES) 2009 cohort, to better understand the relations between teacher-child interactions, classroom context, and DLLs' school readiness; 2) To describe associations between Spanish use by Head Start teachers in the classroom and measures of classroom quality on DLL children's school readiness using secondary data from the FACES 2009 cohort study and a local sample; 3) To examine whether the associations between teacher-child interactions and DLL children's school readiness differ depending on classroom setting and DLL classroom composition, controlling for child and family characteristics using secondary and primary data; 4) To describe teachers' language ideologies and understand possible links to classroom practice and DLLs' student success through collection of primary qualitative data and analysis using qualitative methodology. Findings from this study will inform ways to support the language and socio-emotional development of DLLs. Sample: Primary Data: East Boston Head Start, a program consisting of 12 preschool classrooms with 221 children enrolled. The predominant language and culture is Spanish/Central and South American (73% of families identify as Hispanic). Observations of teacher-child interactions, DLLs' English and Spanish proficiency, and teacher ratings of children's socio-emotional competence will be collected for 120 -140 Latino DLLs. Semi-structured interviews will be conducted with at least 12 teachers and/or teacher assistants. Secondary Data: Participants in the FACES 2009 cohort which included 60 programs, 129 centers, 486 classrooms, and 3,149 children. Included were 919 children whose first language was Spanish. Measures: Child-level assessments of school readiness ? English and Spanish language abilities ? Socio-emotional skills ? Preschool Learning Behaviors Scale (PLBS) Teacher-child interactions ? Classroom quality at the individual level (Primary Data) ? Global classroom quality (Secondary Data) ? Teachers' use of Spanish in the classroom Classroom context ? DLL classroom composition ? Amount of time spent on activity setting (Primary Data); Language used by activity setting (Secondary Data) Family and child demographics ? Demographic questionnaire(Primary Data)Child gender, age, special education status (Secondary Data) ? Child's initial level of English and Spanish proficiency (Secondary Data) ? Family Socioeconomic Status [SES] (Secondary Data)